Prevention and management of intra-operative pain during caesarean section under neuraxial anaesthesia: a technical and interpersonal approach

A woman who experiences pain during caesarean section under neuraxial anaesthesia is at risk of adverse psychological sequelae. Litigation arising from pain during caesarean section under neuraxial anaesthesia has replaced accidental awareness under general anaesthesia as the most common successful medicolegal claim against obstetric anaesthetists. Generic guidelines on caesarean section exist, but they do not provide specific recommendations for this area of anaesthetic practice. This guidance aims to offer pragmatic advice to support anaesthetists in caring for women during caesarean section. It emphasises the importance of non-technical skills, offers advice on best practice and aims to encourage standardisation. The guidance results from a collaborative effort by anaesthetists, psychologists and patients and has been developed to support clinicians and promote standardisation of practice in this area.

The novel Mechanical Ventilator Milano for the COVID-19 pandemic

This paper presents the Mechanical Ventilator Milano (MVM), a novel intensive therapy mechanical ventilator designed for rapid, large-scale, low-cost production for the COVID-19 pandemic. Free of moving mechanical parts and requiring only a source of compressed oxygen and medical air to operate, the MVM is designed to support the long-term invasive ventilation often required for COVID-19 patients and operates in pressure-regulated ventilation modes, which minimize the risk of furthering lung trauma. The MVM was extensively tested against ISO standards in the laboratory using a breathing simulator, with good agreement between input and measured breathing parameters and performing correctly in response to fault conditions and stability tests. The MVM has obtained Emergency Use Authorization by U.S. Food and Drug Administration (FDA) for use in healthcare settings during the COVID-19 pandemic and Health Canada Medical Device Authorization for Importation or Sale, under Interim Order for Use in Relation to COVID-19. Following these certifications, mass production is ongoing and distribution is under way in several countries. The MVM was designed, tested, prepared for certification, and mass produced in the space of a few months by a unique collaboration of respiratory healthcare professionals and experimental physicists, working with industrial partners, and is an excellent ventilator candidate for this pandemic anywhere in the world.

South African Society of Anaesthesiologists Perioperative Patient Blood Management Guidelines 2020

Anaesthesiologists regularly request and administer blood components to their patients, a potentially life-saving intervention. All anaesthesiologists must be familiar with the indications and appropriate use of blood and blood components and their alternatives, but close liaison with haematologists and their local haematology blood sciences laboratory is encouraged. In the last decade, there have been considerable changes in approaches to optimal use of blood components, together with the use of alternative products, with a need to update previous guidelines and adapt them for anaesthesiologists working throughout the hospital system.

First Results from the DEAP-3600 Dark Matter Search with Argon at SNOLAB

This Letter reports the first results of a direct dark matter search with the DEAP-3600 single-phase liquid argon (LAr) detector. The experiment was performed 2 km underground at SNOLAB (Sudbury, Canada) utilizing a large target mass, with the LAr target contained in a spherical acrylic vessel of 3600 kg capacity. The LAr is viewed by an array of PMTs, which would register scintillation light produced by rare nuclear recoil signals induced by dark matter particle scattering. An analysis of 4.44 live days (fiducial exposure of 9.87 ton day) of data taken during the initial filling phase demonstrates the best electronic recoil rejection using pulse-shape discrimination in argon, with leakage <1.2×10^{-7} (90% C.L.) between 15 and 31  keV_{ee}. No candidate signal events are observed, which results in the leading limit on weakly interacting massive particle (WIMP)-nucleon spin-independent cross section on argon, <1.2×10^{-44}  cm^{2} for a 100  GeV/c^{2} WIMP mass (90% C.L.).

Host Responses to Biofilm

From birth to death the human host immune system interacts with bacterial cells. Biofilms are communities of microbes embedded in matrices composed of extracellular polymeric substance (EPS), and have been implicated in both the healthy microbiome and disease states. The immune system recognizes many different bacterial patterns, molecules, and antigens, but these components can be camouflaged in the biofilm mode of growth. Instead, immune cells come into contact with components of the EPS matrix, a diverse, hydrated mixture of extracellular DNA (bacterial and host), proteins, polysaccharides, and lipids. As bacterial cells transition from planktonic to biofilm-associated they produce small molecules, which can increase inflammation, induce cell death, and even cause necrosis. To survive, invading bacteria must overcome the epithelial barrier, host microbiome, complement, and a variety of leukocytes. If bacteria can evade these initial cell populations they have an increased chance at surviving and causing ongoing disease in the host. Planktonic cells are readily cleared, but biofilms reduce the effectiveness of both polymorphonuclear neutrophils and macrophages. In addition, in the presence of these cells, biofilm formation is actively enhanced, and components of host immune cells are assimilated into the EPS matrix. While pathogenic biofilms contribute to states of chronic inflammation, probiotic Lactobacillus biofilms cause a negligible immune response and, in states of inflammation, exhibit robust antiinflammatory properties. These probiotic biofilms colonize and protect the gut and vagina, and have been implicated in improved healing of damaged skin. Overall, biofilms stimulate a unique immune response that we are only beginning to understand.

MC1R genotype as a predictor of early-onset melanoma, compared with self-reported and physician-measured traditional risk factors: an Australian case-control-family study

Background

Melanocortin-1 receptor (MC1R) gene variants are very common and are associated with melanoma risk, but their contribution to melanoma risk prediction compared with traditional risk factors is unknown. We aimed to 1) evaluate the separate and incremental contribution of MC1R genotype to prediction of early-onset melanoma, and compare this with the contributions of physician-measured and self-reported traditional risk factors, and 2) develop risk prediction models that include MC1R, and externally validate these models using an independent dataset from a genetically similar melanoma population.

Methods

Using data from an Australian population-based, case-control-family study, we included 413 case and 263 control participants with sequenced MC1R genotype, clinical skin examination and detailed questionnaire. We used unconditional logistic regression to estimate predicted probabilities of melanoma. Results were externally validated using data from a similar study in England.

Results

When added to a base multivariate model containing only demographic factors, MC1R genotype improved the area under the receiver operating characteristic curve (AUC) by 6% (from 0.67 to 0.73; P < 0.001) and improved the quartile classification by a net 26% of participants. In a more extensive multivariate model, the factors that contributed significantly to the AUC were MC1R genotype, number of nevi and previous non-melanoma skin cancer; the AUC was 0.78 (95% CI 0.75-0.82) for the model with self-reported nevi and 0.83 (95% CI 0.80-0.86) for the model with physician-counted nevi. Factors that did not further contribute were sun and sunbed exposure and pigmentation characteristics. Adding MC1R to a model containing pigmentation characteristics and other self-reported risk factors increased the AUC by 2.1% (P = 0.01) and improved the quartile classification by a net 10% (95% CI 1-18%, P = 0.03).

Conclusions

Although MC1R genotype is strongly associated with skin and hair phenotype, it was a better predictor of early-onset melanoma than was pigmentation characteristics. Physician-measured nevi and previous non-melanoma skin cancer were also strong predictors. There might be modest benefit to measuring MC1R genotype for risk prediction even if information about traditional self-reported or clinically measured pigmentation characteristics and nevi is already available.

Seasonal changes in physical performance and heart rate variability in high level futsal players

The aim of this study was to determine the changes in physical performance and resting heart rate variability (HRV) in professional futsal players during the pre-season and in-season training periods. 11 athletes took part in the study (age=24.3±2.9 years; height=176.3±5.2 cm; weight=76.1±6.3 kg), and performed a repeated-sprint ability (RSA) test [6×40 m (20+20 m with a 180° change of direction) sprints separated by 20 s of passive recovery] and Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) at 3 different moments (M1=beginning of pre-season; M2=end of pre-season; M3=mid in-season). The HRV indices were assessed at the same moments. After the short pre-season (3-week), mean RSA time (RSAmean) (M1=7.43±0.2 s; M2=7.24±0.2 s; P=0.003), decrement in RSA performance (RSAdecrement) (M1=6.7±0.3%; M2=5.0±0.9%; P=0.001), and Yo-Yo IR1 distance (M1=1.244±298 m; M2=1.491±396 m; P=0.002) were significantly improved (P<0.05). During the in-season (i. e., M3), performance in Yo-Yo IR1 and RSAmean were maintained. In contrast, RSAbest (M2=6.89±0.2 to M3=6.69±0.3; P=0.001) was improved and RSAdecrement (M2=5.0±0.9% to M3=6.6±0.9%; P=0.001) was impaired. At M2, there was an increase in HRV vagal-related indices compared with M1 that was maintained at M3. In conclusion, after a short pre-season, futsal players improved their RSA and Yo-Yo IR1 performance with concomitant improvements in HRV. These indices were maintained during the in-season period while RSAbest was improved and RSAdecrement impaired. Frequent monitoring of these performances and HRV indices may assist with identification of individual training adaptations and/or early signs of maladaption.

Strontium- and magnesium-enriched biomimetic β-TCP macrospheres with potential for bone tissue morphogenesis

During the last two decades, biogenic mineral ions have become important additives in treatments for bone regeneration and repair. Prominent among these is strontium, which is a potent suppressor of osteoclast bone resorption. Another is magnesium, which has a key influence in mineralization processes. The shells of benthic foraminiferans, hydrothermally converted into β-TCP, have been shown to effectively release a number of bone-promoting drugs at clinically relevant levels. In this study we characterized the effects of converted foraminiferan calcium dissolution and the concomitant release profile of intrinsic strontium and magnesium. We tested the effects of strontium- and magnesium-enriched macrospheres on human osteoblast (SaOS-2) and monocytoid (U937) cell lines, which can be induced to express equivalent phagocytic activities to osteoclasts. On dissolution in a biomimetic physiological solution, the macrospheres released biologically significant quantities of calcium and phosphate ions in the first 18 days. At 3 days, during which biogenic mineral ions are released, the number of U937 osteoclast-like monocyte cells decreased, while 4 days later the osteoblast cell number increased. These results show that strontium and magnesium naturally enriched macrospheres are capable of altering the metabolic activities of the cells regulating bone homeostasis. These unique macrospheres are natural origin bone void filler particles that resorb, and release physiologically significant levels of incorporated strontium, magnesium and calcium, which together make a uniquely multifunctional in situ remedy for bone regeneration and repair and the treatment of bone-wasting diseases.

Prospective parallel randomized trial of the MultiCyte™ ThinPrep(®) imaging system: the Scottish experience

BACKGROUND

Computer-assisted screening of cervical liquid-based cytology (LBC) preparations using the ThinPrep® Imaging System (TIS) has shown improved qualitative and quantitative gains. The use of Multicyte™ has not been described in a well-established national screening programme with a low incidence of high-grade dyskaryosis.

OBJECTIVES

To assess the impact of computer-assisted screening within the Scottish Cervical Screening Programme (SCSP).

METHODS

Two groups of three laboratories, each sharing a ThinPrep® Imager, screened 79 366 slides randomized to test and 90 551 to control arms by laboratory accession. Screeners were not blinded. Standard laboratory reporting profiles of the SCSP, sensitivity, specificity and false-negative rates of all grades of LBC abnormalities with respect to final cytology reports, predictive value for cervical intraepithelial neoplasia grade 2 or worse (CIN2+) on histology; and screening rates were compared for both arms.

RESULTS

Inadequate and negative reporting rates were significantly lower and low-grade reporting rates significantly higher in the imager arm. Imager-assisted screening showed significantly better specificity than manual screening with respect to the final cytology result. There was no evidence of a significant difference in the detection of CIN2+ or CIN3 +. Positive, abnormal and total predictive values (high-grade, low-grade and all abnormal cytology found to be CIN2+, respectively) were similar in both arms. Productivity was significantly higher in the imager arm.

CONCLUSION

  Computer-assisted screening in a well established screening programme showed significantly improved productivity without loss of quality. These findings should inform future policy for cervical screening programmes.

Listening to music in the first, but not the last 1.5 km of a 5-km running trial alters pacing strategy and improves performance

We examined the effects of listening to music on attentional focus, rating of perceived exertion (RPE), pacing strategy and performance during a simulated 5-km running race. 15 participants performed 2 controlled trials to establish their best baseline time, followed by 2 counterbalanced experimental trials during which they listened to music during the first (M start) or the last (M finish) 1.5 km. The mean running velocity during the first 1.5 km was significantly higher in M start than in the fastest control condition (p<0.05), but there was no difference in velocity between conditions during the last 1.5 km (p>0.05). The faster first 1.5 m in M start was accompanied by a reduction in associative thoughts compared with the fastest control condition. There were no significant differences in RPE between conditions (p>0.05). These results suggest that listening to music at the beginning of a trial may draw the attentional focus away from internal sensations of fatigue to thoughts about the external environment. However, along with the reduction in associative thoughts and the increase in running velocity while listening to music, the RPE increased linearly and similarly under all conditions, suggesting that the change in velocity throughout the race may be to maintain the same rate of RPE increase.

Physiological responses to shuttle repeated-sprint running

This study investigated the influence of 180 degrees changes of direction during a repeated-sprint running test on performance, cardiorespiratory variables, muscle deoxygenation and post-exercise blood lactate ([La] (b)) levels. Thirteen team-sport athletes (22+/-3 yr) performed 6 repeated maximal sprints with (RSS, 6 x[2 x 12.5 m]) or without (RS, 6 x 25 m) changes of direction. Best and mean running time, percentage speed decrement (%Dec), pulmonary oxygen uptake ( V O (2)), vastus lateralis deoxygenation (Hb (diff)) and [La] (b) were calculated for each condition. Best and mean times for both protocols were largely correlated (r =0.63 and r =0.78, respectively), and were 'ALMOST CERTAINLY' higher for RSS compared with RS (e. g., 5.30+/-0.17 vs. 4.09+/-0.17 s for mean time, with the qualitative analysis revealing a 100% chance of RSS time being greater than RS). In contrast, %Dec was 'POSSIBLY' lower for RSS (2.6+/-1.2 vs. 3.2+/-1.3%, with a 79% chance of a real difference). Compared with RS, V O (2) (40.4+/-4.2 vs. 38.9+/-3.8 mL x min (-1) x kg (-1), with a 90% chance of a real difference) and [La] (b) (10.0+/-1.7 vs. 9.3+/-2.4 mmol.L (-1), with a 70% chance of a real difference) were 'POSSIBLY' higher. Conversely, there were no differences in Hb (diff) (11.5+/-3.2 vs. 10.9+/-3.0 microM, with the comparison rated as 'UNCLEAR'). To conclude, the present results suggest that the ability to repeat sprints can be considered as a general quality. They also suggest that repeated shuttle sprints might be an effective training practice for eliciting a greater systemic physiological load, but perhaps not a greater loading of the vastus lateralis.

Turning down lipid oxidation during heavy exercise--what is the mechanism?

A high potential for lipid oxidation is a sign of metabolic fitness and is important not only for exercise performance but also for health promotion. Despite considerable progress during recent years, our understanding of how lipid oxidation is controlled remains unclear. The rate of lipid oxidation reaches a peak at 50-60% of V(O2 max) after which the contribution of lipids decreases both in relative and absolute terms. In the high-intensity domain (>60% V(O2 max)), there is a pronounced decrease in energy state, which will stimulate the glycolytic rate in excess of the substrate requirements of mitochondrial oxidative processes. Accumulation of glycolytic products will impair lipid oxidation through an interaction with the carnitine-mediated transfer of FA into mitochondria. Another potential site of control is Acyl-CoA synthetase (ACS), which is the initial step in FA catabolism. The activity of ACS may be under control of CoASH and energy state. There is evidence that additional control points exist beyond mitochondrial influx of fatty acids. The electron transport chain (ETC) with associated feed-back control by redox state is one suggested candidate. In this review it is suggested that the control of FA oxidation during heavy exercise is distributed between ACS, CPT1, and ETC.

A prospective study of glycaemic status in anti-psychotic-treated patients

Anti-psychotic drugs, particularly the second generation, or ;atypical' agents, have been implicated in the development of metabolic dysfunction such as diabetes mellitus. There is a paucity of longitudinal data on the natural history of glucose homeostasis in anti-psychotic-treated patients, and there are no universally accepted strategies for managing worsening glycaemic control in this population. Notwithstanding, several guidelines recommend switching to a ;lower risk' agent if patients develop worsening glycaemic control during anti-psychotic treatment. We prospectively followed a cohort of 106 anti-psychotic-treated patients from across the diagnostic spectrum, and investigated changes in glycaemic status. Between baseline and follow-up assessment (mean follow-up time, 599.3 [SD+/-235.4] days glycaemic status was unchanged in 78 (86.7%) patients; 5 (5.6%) reverted from impaired fasting glucose (IFG) to normoglycaemia in the absence of any pharmacological or lifestyle intervention and all were taking a ;high risk' drug (clozapine or olanzapine). These preliminary data suggest that progression to overt diabetes mellitus is not inevitable in patients who develop IFG during anti-psychotic treatment. Switching to another agent simply on the basis of the development of IFG may not offer any advantage, especially if the mental state is stable.

Sprint vs. interval training in football

The aim of this study was to compare the effects of high-intensity aerobic interval and repeated-sprint ability (RSA) training on aerobic and anaerobic physiological variables in male football players. Forty-two participants were randomly assigned to either the interval training group (ITG, 4 x 4 min running at 90 - 95 % of HRmax; n = 21) or repeated-sprint training group (RSG, 3 x 6 maximal shuttle sprints of 40 m; n = 21). The following outcomes were measured at baseline and after 7 weeks of training: maximum oxygen uptake, respiratory compensation point, football-specific endurance (Yo-Yo Intermittent Recovery Test, YYIRT), 10-m sprint time, jump height and power, and RSA. Significant group x time interaction was found for YYIRT (p = 0.003) with RSG showing greater improvement (from 1917 +/- 439 to 2455 +/- 488 m) than ITG (from 1846 +/- 329 to 2077 +/- 300 m). Similarly, a significant interaction was found in RSA mean time (p = 0.006) with only the RSG group showing an improvement after training (from 7.53 +/- 0.21 to 7.37 +/- 0.17 s). No other group x time interactions were found. Significant pre-post changes were found for absolute and relative maximum oxygen uptake and respiratory compensation point (p < 0.05). These findings suggest that the RSA training protocol used in this study can be an effective training strategy for inducing aerobic and football-specific training adaptations.

Are there differences in performance, metabolism, and quadriceps muscle activity in black African and Caucasian athletes during brief intermittent and intense exercise?

The purpose of the present study was to determine whether there are any differences in power output (PO) and/or quadriceps muscle (Quad) activity between black African and Caucasian football players during a force-velocity (fv) exercise test, which consisted of performing maximal 6-s sprints against an increasing load. Each subject started the test with a load of 2 kg and then recovered for 5 min before repeating the same test with a load increased by 2 kg. When the pedal frequency did not exceed 130 rev x min(-1), the load was increased by only 1 kg. Each subject attained the load corresponding to his maximal power if an additional increase in load (+1 kg) induced a power decrease. Nine black Africans (mean age 24.2 +/- 3.3 years) and nine Caucasians (24.7 +/- 4.2 years) (matched for stature and aerobic fitness) participated in the fv exercise test. During the test, PO, blood lactate, and the quadriceps electromyography (EMG) root mean square (Quad RMS) were assessed. Higher blood lactate was observed in Caucasians than in black Africans for POs over the load range from 4 kg up to the maximal power. However, PO and Quad RMS values were similar in Caucasians and black Africans. They also had similar lean leg volume (LLV) and consequently produced similar PO/LLV and Quad RMS/LLV values. Overall, our results suggest that Caucasians and black Africans matched for stature, VO(2max), and training background have similar PO and Quad RMS values, but different blood lactate concentrations during brief, intermittent, intense exercise performed on a cycloergometer.

Effects of rest interval during high-repetition resistance training on strength, aerobic fitness, and repeated-sprint ability

The effect of altering the rest period on adaptations to high-repetition resistance training is not well known. Eighteen active females were matched according to leg strength and repeated-sprint ability and randomly allocated to one of two groups. One group performed resistance training with 20-s rest intervals between sets, while the other group employed 80-s rest intervals between sets. Both groups performed the same total training volume and load. Each group trained 3 days a week for 5 weeks [15- to 20-repetition maximum (RM), 2 - 5 sets]. Repeated-sprint ability (5x6-s maximal cycle sprints), 3-RM leg press strength, and anthropometry were determined before and after each training programme. There was a greater improvement in repeated-sprint ability after training with 20-s rest intervals (12.5%) than after training with 80-s rest intervals (5.4%) (P = 0.030). In contrast, there were greater improvements in strength after training with 80-s rest intervals (45.9%) than after training with 20-s rest intervals (19.6%) (P = 0.010). There were no changes in anthropometry for either group following training. These results suggest that when training volume and load are matched, despite a smaller increase in strength, 5 weeks of training with short rest periods results in greater improvements in repeated-sprint ability than the same training with long rest periods.

Validity of simple field tests as indicators of match-related physical performance in top-level professional soccer players

The aim of this study was to examine the construct validity of selected field tests as indicators of match-related physical performance. During the competitive season, eighteen professional soccer players (age 26.2 +/- 4.5 yrs, mass 80.8 +/- 7.8 kg, and height 181.9 +/- 3.7 cm) completed an incremental running field test to exhaustion, a vertical-jump and a repeated-sprint ability (RSA) test. Match physical performance was quantified during official matches using a video-computerized, semi-automatic, match analysis image recognition system, (ProZone, Leeds, UK). The selected measures of match physical performance were: total distance covered (TD), high intensity running (HIR: > 14.4 km . h (-1)), very high intensity running (VHIR:> 19.8 km . h (-1)), sprinting (> 25.2 km . h (-1)) and top running speed. Significant correlations were found between peak speed reached during the incremental field test and TD (r = 0.58, R (2) = 0.34; p < 0.05), HIR (r = 0.65, R (2) = 0.42; p < 0.01) and VHIR (r = 0.64, R (2) = 0.41; p < 0.01). Significant correlations were also found between RSA mean time and VHIR (r = - 0.60, R (2) = 0.36; p < 0.01) and sprinting distance (r = - 0.65, R (2) = 0.42; p < 0.01). Significant differences were found between the best and worst group as defined by the median split technique for peak speed (TD = 12 011 +/- 747 m vs. 10 712 +/- 669, HIR = 3192 +/- 482 m vs. 2314 +/- 347 m, and VHIR = 1014 +/- 120 vs. 779 +/- 122 m, respectively; p < 0.05) and RSA mean time (VHIR = 974 +/- 162 m vs. 819 +/- 144 m, and sprinting = 235 +/- 56 vs. 164 +/- 58 m, respectively; p < 0.05). In conclusion, this study gives empirical support to the construct validity of RSA and incremental running tests as measures of match-related physical performance in top-level professional soccer players.

Reliability of a 5 × 6-s maximal cycling repeated-sprint test in trained female team-sport athletes

The present study examined the reliability of work and power measures during a 5 x 6-s cycle ergometer test of repeated-sprint ability. Nine, well-trained, female soccer players performed five, 5 x 6-s repeated-sprint tests on a front-access cycle ergometer on separate days. Sprints were separated by 24 s of active recovery. Absolute measures of total work done (W (tot)), total peak power (PP(tot)), work done during sprint 1 (W (1)) and peak power output during sprint 1 (PP(1)) were recorded. Decrement scores in work done (W (dec)) and peak power output (PP(dec)), and fatigue indices for work done (FI( W )) and peak power (FI( P )), were calculated. Significant improvements in all of the work and power measures were observed between trial 1 and subsequent trials (P < 0.05), but no significant differences were identified between trials 2, 3, 4 and 5. The same was true for increases in the decrement scores. The coefficient of variation (CV) was established to reflect within-subject reproducibility for each variable. The CV was significantly improved by the third trial for work done (W (tot) CV: trials 1-2 = 5.5%; trials 3-4 = 2.8%), peak power (PP(tot) CV: trials 1-2 = 5.1%; trials 3-4 = 2.7%) and performance decrement scores (P < 0.05). The standard error of measurement (SEM) and intraclass correlation coefficient (ICC) were also calculated for each variable and expressed within 95% confidence intervals. It was concluded that two familiarisation trials are optimal for collecting reliable data from a 5 x 6-s repeated-sprint cycling test. Furthermore, due to the large variation around performance decrement it was suggested that decrement scores ought to be interpreted with caution.

Comparison of the VO2 response to 800-m, 1500-m and 3000-m track running events

AIM

The present study examined the VO2 response to middle-distance track running events of 800 m, 1500 m and 3000 m and investigated the relationship between the speed of the VO2 response ((1) and subsequent race performance.

METHODS

Trained 3000-m (n = 8), 1500-m (n = 10) and 800-m (n = 8) male track athletes performed a laboratory GXT plus a run at 14 km x h(-1) and multiple race time trials. For each subject, a bi-exponential model fit from 20 s was used to categorise the O2 response for the best performed track run and also the treadmill run at 14 km x h(-1).

RESULTS

Faster (1 values were noted the shorter the track event, with values of 14, 18.5 and 20.8 s for 800-, 1500- and 3000-m events, respectively. ANOVA results revealed that differences in (1 were significant (P < 0.05) for the 800- and 3000-m, but not for the 800- and 1500-m (P = 0.06) or 1500- and 3000-m events (P = 0.15). Only 1500-m race performance was significantly correlated to race (1 (r = 0.71). Values for (1 at an absolute velocity treadmill run (14 km x h(-1)) did not differ significantly between different events and were not correlated to race performance for any event. From pooled data for all three events, significant correlations (P < 0.01) were noted between tau1 and the speed over the first 800-m (r = -0.54 to -0.68).

CONCLUSIONS

There was a trend for faster (1values the shorter the track event. The significant correlation between tau1 and initial starting velocity suggests this may be attributed to the faster starting velocity of the shorter track events, rather than any differences between athletes per se.

Variable power output during cycling improves subsequent treadmill run time to exhaustion

The aim of this study was to investigate the effect of constant versus variable power output cycling exercise on subsequent high-intensity, running performance. Eight triathletes completed two testing sessions (in a random order), which required the subjects to perform 30 min of cycling at either, a constant power output (90% of the lactate threshold), or a variable power output with power output alternating every 5 min (+/-20% of the constant workload). Each cycling bout was immediately followed by a high-intensity treadmill run (16.7+/-0.7 km h(-1)) to exhaustion. No significant differences were found for mean metabolic values or power output between cycling conditions. However, a significant (P<0.05) improvement in run time to exhaustion was reported after 30 min of variable cycling (15:09+/-4:43 min) compared to constant cycling (10:51+/-3:32 min). The results of this study demonstrate that, despite similar average physiological responses during 30 min of cycling, variable-intensity cycling results in an improved running performance compared to constant-intensity cycling. It is hypothesised that the reduced power output in the final 5 min of variable cycling protocol may allow recovery before transition, however the mechanisms involved cannot be determined from the current study.

Core temperature and hydration status during an Ironman triathlon

BACKGROUND

Numerous laboratory based studies have documented that aggressive hydration strategies (approximately 1-2 litres/h) are required to minimise a rise in core temperature and minimise the deleterious effects of hyperthermia on performance. However, field data on the relations between hydration level, core body temperature, and performance are rare.

OBJECTIVE

To measure core temperature (Tcore) in triathletes during a 226 km Ironman triathlon, and to compare Tcore with markers of hydration status after the event.

METHOD

Before and immediately after the 2004 Ironman Western Australia event (mean (SD) ambient temperature 23.3 (1.9) degrees C (range 19-26 degrees C) and 60 (14)% relative humidity (44-87%)) body mass, plasma concentrations of sodium ([Na+]), potassium ([K+]), and chloride ([Cl-]), and urine specific gravity were measured in 10 well trained triathletes. Tcore was measured intermittently during the event using an ingestible pill telemetry system, and heart rate was measured throughout.

RESULTS

Mean (SD) performance time in the Ironman triathlon was 611 (49) minutes; heart rate was 143 (9) beats/min (83 (6)% of maximum) and Tcore was 38.1 (0.3) degrees C. Body mass significantly declined during the race by 2.3 (1.2) kg (-3.0 (1.5)%; p < 0.05), whereas urine specific gravity significantly increased (1.011 (0.005) to 1.0170 (0.008) g/ml; p < 0.05) and plasma [Na+], [K+], and [Cl-] did not change. Changes in body mass were not related to finishing Tcore (r = -0.16), plasma [Na+] (r = 0.31), or urine specific gravity (r = -0.37).

CONCLUSION

In contrast with previous laboratory based studies examining the influence of hypohydration on performance, a body mass loss of up to 3% was found to be tolerated by well trained triathletes during an Ironman competition in warm conditions without any evidence of thermoregulatory failure.

Time-motion analysis of elite field hockey during several games in succession: a tournament scenario

International field hockey tournaments may require teams to play three games within a period of four days. Therefore, there is potential for residual fatigue to affect the movement patterns of players during subsequent games. The purpose of this study was to document changes in time-motion analysis of 14 elite male field hockey players during three games within a period of four days during an international tournament. In addition, the nature of and any changes in repeated-sprint activity were investigated using a criteria of a minimum of three sprints with a mean recovery duration between sprints of < 21 s. The percent of total game time spent standing significantly increased across all three games (7.4+/-.2, 11.2+/-2.7 and 15.6+/-5.6%, respectively, P<0.05). Conversely, the percent time spent jogging significantly decreased from game 1 to game 2 and from game 1 to game 3 (40.5+/-7.3, 34.8+/-7.4 and 29.4+/-5.7%, respectively, P<0.05). Furthermore, the percent time in striding significantly increased from game 1 to game 3 and from game 2 to game 3 (4.1+/-1.3, 5.1+/-0.9 and 5.8+/-1.4%, respectively. P<0.05). Changes in mean motion frequency and duration were recorded across games for the motions of standing, striding and sprinting. The frequency of exercise bouts that met the criteria for 'repeated-sprint' decreased across the three games (17, 11 and 8, respectively). In summary, the results suggest that when elite field hockey players play three games within four days there are significant changes in time-motion analysis.